The assistance will provide victims with an initial ration of 400 grams (14 ounces) of maize a day for 14 days, the UN body said in a statement posted Friday on its website.
It said a UN mission that travelled to flood-hit regions earlier in the week found considerable damage to maize, soybean and rice fields.
The country struggles to feed its people even in normal times and suffered a famine in the 1990s that killed hundreds of thousands.
The UN mission said immediate food aid was needed for residents of the worst-hit counties, Anju and Songchon in South Pyongan province and Chonnae in Kangwon province.